Parentage: The Rosa hybrida variety ‘KORtragoso’ is the result of a controlled cross-pollination breeding program carried out by the inventor in Klein Offenseth-Sparrieshoop, Germany. The objective of the said breeding program was to create a new and distinct rose plant with unique qualities, such as:                1. Uniform growth and flowering; and        2. Abundant, recurrent yellow and red bicolor flowers; and        3. Attractive and abundant foliage; and        4. Resistance to diseases encountered in landscapes and gardens.This combination of qualities is not present in prior rose cultivars known to the inventor. These objectives have been substantially achieved and in that distinguish ‘KORtragoso’ from all other varieties known to the inventor.        
‘KORtragoso’ is a seedling selection which resulted from the controlled pollination of an unnamed Rosa hybrida breeding line, the seed parent, with another unnamed Rosa hybrida breeding line, the pollen parent, during the summer of 2005. Both breeding lines were developed and owned by the same inventor. As part of a rose development program, Tim-Hermann Kordes germinated seeds from the aforementioned hybridization during the following winter and conducted evaluations and observations on the resulting seedlings in a controlled environment in Klein Offenseth-Sparrieshoop, Germany. The resulting seedlings exhibited distinctive physical and biological characteristics. The new rose plant was selected as a single plant in May of 2006 from the seedling beds due to its superior characteristics and asexually propagated for further evaluation. This new and distinctive rose variety was given the name ‘KORtragoso’.
Asexual Reproduction: ‘KORtragoso’ was first asexually propagated by bud grafting in July of 2006 at the inventor's nursery in Klein Offenseth-Sparrieshoop, Germany. Subsequently, ‘KORtragoso’ has been successfully propagated by stem cuttings and bud grafting in Jackson County, Oreg. These initial and other subsequent propagations conducted in controlled environments demonstrate that ‘KORtragoso’ reproduces true to type in successive generations of asexual reproduction.